In a mobile terminal such as a mobile phone, a personal handy phone system (PHS), and a personal digital assistant (PDA), a tendency toward downsizing and thinning is being accelerated. In order to achieve the downsizing and thinning of such mobile terminals described above, development has been advanced about downsizing and thinning of functional components for forming the same, thinning of a printed circuit board on which the functional components are mounted, downsizing of an antenna system, a reduction in wall thickness and thinning of a casing accommodating the functional components, the printed circuit board, etc., and the like.
FIG. 8 is a sectional view of the switch section of a conventional mobile terminal. The structure shown in FIG. 8 might be similar to an elastically deformable switch dome (conductor) that is illustrated by 524 in Patent Document 1 (JP 2004-96057 A) and that is reversed upside down. A conductor 124 is arranged so that the conductor 124 is covered with a cover sheet 102B along a recess 111 provided in a casing 127 and is fixed with the cover sheet 102B. A switch button sheet 102A is arranged over the conductor 124, and a switch button 125 and a top plate 106 are arranged over the switch button sheet 102A. The conductor 124 and a protruding part 112 are situated in the recess 111.
When the switch button 125 is depressed, a periphery of the switch button 125 pushes down an entire contour of the conductor 124, with the periphery of the switch button 125 supported by the supported sections 113, and as a result, a click operation is performed due to the protruding part 112, whereby the switch circuit is operated. In an example shown in the figure, the casing 127 is to be produced by molding.
The structure is characterized in that the supporting sections 113 are arranged around a plurality of the protruding parts 112 so as to provide a single plane. That is, the peripheries of the supporting sections 113 are continuous with each other on the same plane. Thus, the support area for the switch sheet has a wide area.